A cooling system using as a coolant water without antifreeze, such as the conventional system of a diesel locomotive, functions effectively in warm weather and while the locomotive's engine is running but must be dumped whenever the engine unexpectedly, unintentionally or accidentally shuts down and the ambient air temperature is approaching freezing, to prevent damage to the cooling system and the engine. Compressed air-operated dump valves for dumping the water coolant of such a system, were introduced around 1970 but, because manually controlled, were not practical for dumping the coolant in an emergency, as when an engine of a single locomotive or locomotive consist unexpectedly or unintentionally shut down.
A proposed solution for the problem was the dual-winding solenoid-actuated dump valve of Frantz et al patent U.S. Pat. No. 4,065,096, issued Dec. 27, 1977. As opposed to a conventional single-winding solenoid whose power output was inadequate to open a dump valve, the solenoid of the above patent, with separate high and low power windings, ordinarily could both open the dump valve against a considerable hydraulic head and a retaining spring and hold it open until the water coolant was completely drained. A difficulty with the valve of the Frantz patent as an emergency dump valve was that it was not reliable in operation under all service conditions.
The concern of the present invention is an improvement on prior dump valves which is fully automatic in operation and effective to dump from a cooling system a water coolant containing no antifreeze whenever an emergency arises.